I thought that too before I decided to try it. Some amps, like my 50W Mesa Express, get really loud for a smaller room long before you get to '1' on the MV, and the tone is pretty crappy at those settings. I use the JHS LBB in the loop to just trim enough off the signal to keep the overall volume reasonable (90-100 dB at 6 feet) when the amp's MV is around '3'. Believe it or not, the resulting tone is much better than having the MV extremely low. It seems to just open up the amp enough to sound really good. Different story with my 50W Rectifier. It has a MV for each channel as well as an 'Output' volume control, which acts as an overall MV for the amp. This seems to give much better control and that amp sounds good at lower volume on its own.